Well there's some utility in SMN like crimson cyclone or landslide which can be used to interrupt most of channeling spells in dungeon. that was the case but,

the most frustrating thing for me as a summoner was the casting mechanics which prevent SMN/SCH to issue any order to the pet while channeling theirr spells. for instance when i cast bio II and all of sudden the boss/mobs start to channel spell which can be prevented (by ordering ifrit/titan to stun), guess what ? we can't do it easily because we need to interrupt our channel sequence and then gave order which in turn takes extra time to interrupt any channeling spells, in addition the summon seems to take a bit time before executing a given order. They need to fix this mechanic since it blunting the edge SMN has
Note: warr/lnc can easily switch their attack to stun in middle of animation while summoner can't (because we can freely issue an order) which i consider ridiculous

it was quite surprising that not many people complaining about this, all they care was the damage potency.